Me infront of the ATLAS detector. My name’s Ben and I am a Graduate Materials Engineer in the Technology department at STFC, working in the Composites and Materials Testing Group. As a graduate on the STFC graduate scheme I had the opportunity of arranging a three-month work placement, for which I worked in the Materials and Metrology (MM) department at CERN from September to December 2024. While at CERN, I worked on fundamental material research for the target of the Beam Dump Facility (BDF) and the Search for Hidden Particles (SHiP) experiment, a series of detectors searching for weakly interacting particles and dark matter. It was really exciting to be involved in a project that could ultimately assist in our understanding of dark matter!
The BDF target will constitute a series of cylindrical tungsten blocks cooled by helium. These blocks will be formed by bonding rolled tungsten sheets of varying thickness using a tantalum interlayer and high temperature and pressure, in a process called hot isostatic pressing (HIP). To conduct this work, I collaborated with both the MM and Sources, Targets and Interactions Group (STI) departments at CERN to conduct a preliminary investigation into how the tungsten behaves at the elevated temperatures experienced in the target.
Diagram showing the target within the BDF and SHiP
Before delving into understanding the material properties of the rolled sheets of tungsten, one of my first jobs was to ensure that the received material was of a suitable standard. This exposed me to some interesting non-destructive techniques such as ultrasonic testing, where sound waves and their echoes are used to detect porosities in the material. On top of this I used different optical and electron microscopy techniques to study the microstructure and surface condition of the metal. You can also see some lovely colour changes using these techniques as the thickness of the oxide layer changes when tungsten is exposed to 400 degrees in air!
When in operation, the target will experience constant temperature and stress cycles as it is hit by ten million pulses of high energy protons throughout its lifetime. This cyclic loading causes something called fatigue, which changes the material properties over time. This means that understanding the fatigue behaviour of tungsten at the elevated temperatures experienced in the target is of vital importance to assess its longevity. As both CERN and STFC are unable to perform these tests, I had to perform thorough market research of the testing capabilities of companies and facilities across Europe, having technical discussions with sales representatives and engineers and negotiating quotations with them. This not only gave me great experience in agenda setting and leading meetings but has also increased my knowledge of the testing capabilities in Europe and greatly expanded my network!
Two images of the surface of tungsten at 200x zoom, showing the grain structure and surface colouration after 1 day (left) and 4 days (right) heated in air at 400 degrees.
Conducting nanoindentation on tungsten to assess hardness at depths of just 10nm.It was inspiring to conduct this work alongside world leading scientists and engineers from all over Europe in the MM and STI groups and I have learnt so much about my discipline from each of them. From the start, I was empowered to take control of the project which allowed me to develop my project management capabilities, and guidance and training from my colleagues in MM has taught me some interesting laboratory techniques including nanoindentation and electron backscatter diffraction (EBSD) to name a few. A real highlight was the recognition of my contribution to the project by being co-authored on my first paper!
It was also stimulating to work in a group of just two British people, equally represented by both men and women and one which is embedded in a different working culture. It has further highlighted to me the benefits with respect to open-mindedness and perspective that a diverse team can bring to making thoughtful and informed decision making.
Cycling through the alps with friends to the Grande Dixence dam at over 2000m above sea level.Life in and around CERN is highly sociable and active. I tried to make the most of the large social groups, meeting and networking with people across the institution at lunch and after work on Fridays, running in the vineyards and swimming in the very cold Lake Geneva after work. The weekends brought more excitement, exploring the alpine roads by bike, lodging up in the mountains and experiencing the fun (but expensive) Geneva night life with colleagues and friends.
As a result of this placement, I have developed countless practical and soft skills and made contacts that will serve me well throughout my entire career. I have also learnt about a new branch of materials, giving me knowledge outside of my background in chemistry and making me a more well-rounded materials engineer.
None of this would have been possible without the support of many people here at STFC and at CERN. First, I would like to thank my senior management in the Technology Department for facilitating and funding this opportunity. My thanks also go out to the staff CERN that gave me the opportunity and integrated me into the project so thoughtfully. Finally, my thanks extend to STFC HR representatives and the STFC Graduate Team for their efforts and patience in the organisation of this opportunity and without whom it never would have happened!
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Written by Ben Corbett.
